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-------------------------------- -------------------------------- -------------------------------- -------------------------------- -------------------------------- -------------------------------- -------------------------------- ----flare sizing ----flame stability ----flash back ----pilot system ----noise level |
SMOKELESS OPERATION THE MOST COMMON METHOD TO ACHIEVE SMOKELESS CONDITION IS TO INJECT STEAM INTO THE FLAME.\ THE SPECIFIC REQUIREMENTS FOR STEAM-ASSISTED FLOW OPERATION DEPEND ON THE MOLECULAR WEIGHT, HEATING VALUE, C-H RATIO OF THE GAS & FLARE TIP DESIGN. TYPICAL VALUES RANGE FROM 0.15 TO 0.50 lb STEAM / lb OF FLARE GAS. EPA RECOMMENDS THE FOLLOWING FORMULA FOR ESTIMATING STEAM REQUIREMENT :
WHERE : Qs = STEAM REQUIREMENT , lb / Min. Qf = FLARE GAS FLOW RATE, std.ft3 / Min. Mw = MOLECULAR WEIGHT OF GAS, lb / lb-mol. IT IS IMPORTANT TO NOTE THAT STEAM PRESSURE FOR SMOKELESS OPERATION SHOULD EXCEED 10 PSIG. IF THE STEAM IS INTRODUCED AT PRESSURE BELOW 10 PSIG, THE DESIRED TURBULENCE OR AIR ENTRAINMENT WILL NOT ACHIEVE SMOKELESS OPERATION DUE TO INSUFFICIENT MOMENTUM. ON THE OTHER HAND, TOO MUCH STEAM WILL COOL THE FLAME AND POSSIBLY SNUFF IT OUT. THIS SITUATION MAY RESULT IN FLAME PULSATION AND FLAME INSTABILITY. EXAMPLE : ESTIMATE THE STEAM REQUIREMENT FOR A GAS FLOW RATE OF 300,000 std ft3 / Min. AND MOLECULAR WEIGHT OF 54 lb / lb-mol. SOLUTION : THE AMOUNT OF STEAM NEEDED TO PRODUCE SMOKELESS OPERATION IS : Qs = 1.03 * 10-3 * Qf * Mw = 1.03*10-3 * 300000 * 54 = 16,686 lb / Min. |